The Flash.
Unlike Superman, Batman, Wonder Woman, or Aquaman, the Flash is not a Single-Identity-That-Always-Revamps-Itself (SITARI).
Instead, like the Green Lantern of Earth, the Flash is a Multiple-Identity-That-Usually-Replaces-Itself (MITURI).
MITURIs have a much harder time than SITARIs (which are totally made-up terms that no one else uses), especially when it comes to matching the SITARIs' stability for Supporting casts and rogues galleries.
Speaking of rogues galleries, it's doubly hard for the Flashes' villains to reach the levels of Joker or Luthor.
Part of that, I believe, is because there isn't a clear opposite number across the almost 80 years of the Flashverse.
On the one hand, you have the Evil Speedsters, mainly consisting of The Rival, Reverse-Flash, Zoom, and Savitar.
On the other hand, you have the Evil Coldsters, mainly consisting of The Icicle, Captain Cold, Killer Frost, Chillblaine (ha!), and (though this would be a very controversial franchise-theft, I feel he belongs more here than in Gotham) Mr. Freeze.
Which of these two villain types makes for a better practical arch-enemy?
I get that Eobard has been positioned as the Luthor/Joker of the Flashverse since Barry returned and definitely since the New52 instead Eobard directly into Barry's origin (and removing Jay as any source of inspiration, btw).
But to me, cold represents the opposite of speed. Coldsters cool things down, thereby slowing things down. They should be able to neutralize the overwhelming advantage that speedsters have over non-speedsters (unless PIS is involved).
I kinda wish we had a genuine metahuman with Omega Iceman level powers at DC. Or maybe amp Killer Frost way the heck up, I dunno.
What do you Flash fans think?
Evil Speedster vs Evil Coldster for the Arch-Nemesis Crown?
No poll this time.